1. Technical Field
The invention relates generally to the field of analyzing aggregate mixtures for purposes of determining acceptability of same for use. More specifically, the invention is directed to an improved analysis device suitable for performing multiple analyses on a given test sample of aggregate mixture.
2. Description of Prior Art
Modern roadways, parking lots, airport taxiways and landing strips, sidewalks, and other surfaces designed to accommodate wheeled vehicles are often paved and repaired using a composite material comprised of aggregates and binders. Pavement, concrete, and certified aggregates are comprised of a mixture of aggregates of varying sizes, from fine sand to small rocks, some combined with liquid binder.
Aggregate mixtures may be formulated to have varying properties, including strength, flexibility, water-resistance, cracking resistance, cost-effectiveness, and the like. Required properties for different applications are well known in the art and are subject to extensive industry and governmental regulation and guidelines. These properties are controlled by the proportion of aggregate or aggregate to binder and the physical nature of the aggregate itself. The size, shape, and hardness of the aggregate, along with its moisture content and amount of air entrapped therein, affect the ultimate properties of the resulting aggregate mixture.
Because of the dependency of aggregate mixtures on their correct properties, various formulations have been developed for different applications, and builders will specify the appropriate formulations for their projects. These formulations specify the proportions of various types of coarse to fine aggregates to be included and the ratio of aggregate to binder. However, the aggregate mixtures are not available as “off the shelf” products but rather must be produced and individually blended as per owner specifications from raw materials generally close in time to its use. The quantities of aggregates used is typically measured in tons, while individual pieces may be measured by the millimeter or even less, and thus the input materials can be classified at best only by their presumed gross average characteristics, introducing the potential for error. As a result, the resulting mixture often may not achieve all of the required properties. Testing protocols, therefore, have been devised for determining whether a freshly produced aggregate mixture meets the specified requirements. These protocols involve taking multiple samples of the completed mixture and testing each sample by deconstructing it into its component materials and comparing same to known standards. Different protocols involve weighing the samples and their component materials, measuring aggregate size, measuring moisture content, measuring air voids, and the performance of other tests. Many of these tests are typically performed in laboratories, using multiple large, special purpose devices for the various types of tests.
The known art is replete with devices to test samples of aggregate in order to analyze the properties of the mixture. There are sieving devices to sort aggregates by size, typically coupled with means for weighing the sorted quantities. These sieving devices typically use a vibratory motion to shake the aggregate through the sieves. There are devices which perform ignition testing, in which the binder is burned off. There are devices for measuring the specific gravity of samples, typically using water submersion techniques. There are devices for measuring theoretical maximum densities. Many of these tests are performed under pressure or in heated conditions.
Most of the devices known in the art for performing tests on samples of aggregate mixtures are very large and cannot be easily transported to a job site, and thus time is lost in transporting samples to the devices. Time is also lost in transferring samples from device to device to perform the various tests. Many of the known devices also do not perform their specific tests efficiently, leading to more lost time, as well as being prone to damaging the sample components, which can yield inaccurate results.
There is thus a long-felt need in the industry for a device which addresses the deficiencies in the known art, specifically a device which combines many testing functions in a single small, portable, self-contained unit which performs its tests quickly, efficiently, and accurately.